1. Field of the Invention
The present invention relates to post anchors. More particularly, the present invention relates to post anchors useful in existing concrete and hard material, as well as softer earth.
2. Description of the Related Art
Traffic sign supports, parking meter poles, fence posts and the like are typically installed in hard earth or cement by driving a post anchor or base into a hole drilled in the hard material and then attaching the support or post to the anchor. Also, post anchors are useful in softer soil to provide a steady base for the post. The driving method in softer soil conditions is relatively quick and can be performed with manual tools such as sledgehammers. Most post anchor designs attempt to ensure durability when subjected to weather and forces such as wind load or impact from a vehicle.
There are many conflicting performance requirements for post anchors. If the anchor is light in weight for ease of driving and to reduce costs it may have insufficient strength to withstand forces applied during installation in difficult or hard ground conditions or from impact from an errant vehicle.
Conversely, some anchors may be sufficiently strong to withstand the installation forces or impact forces, yet they are inherently heavy and therefore are difficult to drive due to increased mass absorbing impact energy. Increased mass also results in higher material and transportation costs.
In practice it has been shown that post anchors, even when installed to the correct depth for a particular application, have varying degrees of force applied over their length. For example, the top of the anchor is subject to impact energy and higher bending forces in use, as opposed to the bottom of the anchor. A common anchor design attempts to address the varying strength requirement by telescoping the next larger size of tubing over the top 6-8 inches of the anchor to form a telescoping system. However, these strengthening pieces do not stay attached to the anchor during driving (installation) or transport. Further, the tolerance between the two coaxial parts can make the anchor sloppy, allowing the post to move laterally after installation in the anchor. Attempts at correcting this problem include welding the two coaxial parts together, adding substantial expense to the installation of the anchor, or bolting them together, which is often ineffective. In either case, in the event the post, anchor, or strengthening sleeve is of the perforated type where the fastener must engage aligned holes, joining the three pieces is difficult.
Based on the geology or ground conditions specific to the location (which can vary dramatically over a very small area) where an anchor for a post is desired, the required installation depth can vary. For example, in extremely hard ground conditions such as dry clay, asphalt, etc., the anchor may be driven to a lesser depth, yet still provide sufficient support to the post. In marsh or damp soil condition, the anchor depth and length required increases.
With both square and round shaped anchoring systems, there is a tendency for the anchor to fill up inside with hard packed material during driving into the ground or soil. This material must somehow be removed in order to insert or telescope the post onto the anchor. Also, the post, particularly a heavy post, may fall too far into the anchor when the post is being installed in the anchor in the event the soil material does not come up into the bottom of the anchor during driving. This factor makes it very difficult for an individual, without assistance, to accomplish a post installation with the post telescoped to the correct depth.
When posts are telescoped within a driven anchor, ground water can promote corrosion of the anchor or post and make it difficult to extract the post for repairs or replacement. Further, the anchor or post can become weakened, and fail unexpectedly under normal use.
In the event a square anchor is installed in a core drilling in existing concrete by driving, an annulus is left between the square anchor shape and the round-drilled hole. Conventional methods require the void space to be filled with a sealer or concrete flashing material for aesthetics, adding to the cost of the installation.
There is a need for a more effective post anchor system which meets the following criteria:
(a) Low weight to reduce transport and material costs and to provide ease of installation;
(b) High strength to ensure durability in use, particularly use where vehicle impacts are anticipated, and to ensure durability of the anchor during installation such as by impact driving;
(c) Sealing against ground water infiltration to the post and to prevent ground materials from entering the portion receiving the post during installation of the anchor;
(d) Flexible in design, allowing for one unit to be used alone in existing concrete and hard earth and in connection with another element for softer earth, the connection being made without expensive welds or unreliable fasteners; and
(e) Configured to prevent a post from falling too far into the anchor.
Thus, a modular post anchor adapter solving the aforementioned problems is desired.